The water pressure from a city water system is 60 psi. A pipe drops 15 feet from the main line to the irrigation system's control valve. What will be the static pressure at the valve?

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Quizplus · Accepted Answer

The static pressure at the valve increases due to the height drop, calculated using the formula for pressure due to elevation change in a fluid: $\Delta P = \rho g h$, where $\rho$ is the density of water (approximately 62.4 lb/ft³), $g$ is the acceleration due to gravity (32.2 ft/s²), and $h$ is the height difference (15 ft). The increase in pressure due to the height drop is $62.4 \times 32.2 \times 15 / 144 \approx 6.5$ psi (144 is the conversion factor from square feet to square inches, since pressure is given in psi). Adding this to the original 60 psi gives approximately 66.5 psi.

The Water Pressure from a City Water System Is 60